1. Field of the Invention
The present invention relates to an image pickup apparatus having appointing means for, in an image frame to be picked up, appointing a point or a region to be subjected to a predetermined image process.
2. Related Background Art
In the industrial field of image pickup apparatuses for the general user, such as a camera having a video tape recorder integrated therewith, a variety of techniques have been employed in order to easily obtain excellent images. In recent years, the automatic focusing (AF) function and the automatic exposure (AE) function have been provided as standard functions to eliminate complex operations such as focusing and exposure that must be adjusted whenever the photographing operation is performed. The foregoing functions are typical examples of functions for easily obtaining an image of excellent quality. Since the AF and AE functions are mechanisms with which an image pickup apparatus such as a camera, spontaneously discriminates the photographing state to adjust the position of the lens and diaphragm to be suitable to the discriminated state, the desire of the photographer is not always is correctly reflected in the image. In a case where both a remote subject and a near subject coexist in the frame to be photographed, execution of the AF operation in accordance with information about the overall image pickup frame results in that although focusing of any of the plural subjects can be established, the image pickup apparatus cannot discriminate that the focused subject is the main subject intended to be focused by the photographer. In a case where the main subject is photographed with a background which is the bright sky, execution of the AE operation in accordance with information about the overall frame causes the diaphragm to be adjusted in accordance with the brightness of the sky. As a result, the photographed main subject is undesirably blackened.
In order to overcome the foregoing problems, a method has usually been employed in which range finding and photometry of a subject positioned in the central portion of the frame is performed and the AF and AE operations are performed in accordance with the results of the range finding and photometry. The foregoing methods are based on the fact that a photographer usually places the main subject in the central portion of the frame. However, the foregoing method creates a problem because focusing and exposure of a main subject cannot be performed appropriately if the main subject is placed outside the central portion of the frame.
Accordingly, the applicant of the present invention has disclosed an image pickup apparatus in Japanese Patent Application No. 04-154165. In order to establish optimum focusing and exposure regardless of the position of the main subject in the frame to be picked up, the foregoing image pickup apparatus having a structure where the line of sight of a photographer who is observing the finder is detected; and a main subject can be selected in accordance with the position of the detected line of sight. The foregoing image pickup apparatus enables the position of the main subject to be changed freely in a manner limited to the range finding and photometry region. The position appointing means for selecting the main subject is not limited to the line-of-sight detection means. For example, it might be considered feasible to employ a means, such as a joy stick or a mouse, in which the amounts of movement in two or more axes are synthesized to determine the direction and position of the movement.
In the foregoing case, the image pickup apparatus detects the position of the line of sight of the photographer and moves the range finding and photometry region correspondingly to the detected position. Therefore, it is accurate and convenient when the image pickup apparatus notifies the photographer of the result of the position detection of the photographer""s line of sight and the range finding and photometry region is moved on the basis of the foregoing result so as to be confirmed by the photographer. Accordingly, the applicant of the present invention has suggested a video camera in Japanese Patent Application No. 3-218574 that comprises a means for superimposing the result of the position detection of the photographer""s line of sight on the finder screen.
However, the foregoing conventional line-of-sight detection/range finding and photometry method suffers from a problem that if the line of sight cannot be detected due to spacing of the photographer""s eye from the finder or external noise, the detection of the position of the line of sight is performed undesirably, resulting in range finding and photometry being performed at the wrong position, not aimed by the photographer. Another problem arises in that if the detection of the line of sight has ended in failure due to external noise or the like, the range finding and photometry of a position, which is different from the viewpoint of the photographer who is observing the finder, is performed creating the feeling of incongruity in the photographer.
Accordingly, a first object of the present invention is to provide an image pickup apparatus which is capable of overcoming the foregoing problems and performing the most suitable range finding and photometry process under any photographing condition.
A second object of the present invention is to enable the portion of a region to be subjected to the range finding and photometry processes to be arbitrarily appointed in the frame and to continue the photographing operation even if an error is made in appointing the position.
In order to achieve the foregoing objects, according to one aspect of the present invention, there is provided an image pickup apparatus comprising: position appointing means for appointing an arbitrary position on a display frame of monitor means; detection means for detecting an error in appointment made by the position appointing means; image signal extracting control means for fetching an image signal in a predetermined fixed region in the display frame if the detection means has detected an error in appointment and for extracting an image signal in a region including the position appointed by the position appointing means if the detection means has detected that the state is normal; and adjustment means for adjusting photographing conditions of the image pickup means in accordance with the image signal fetched by the image-signal fetching control means.
According to another aspect of the present invention, there is provided an image processing apparatus comprising: line-of-sight position detection means for detecting the line of sight of an operator in a display frame; region setting means for setting a region, in which a signal is processed at a position of the line of sight in the display frame detected by the line-of-sight position detection means; and a control means for fixing the region, in which the signal is processed at a predetermined position in the frame if the line-of-sight position detection means produces an error in detecting the position of the line of sight.
Thus, the frame for range finding and photometry is moved to follow the photographing position appointed by a photographer of, for example, a video camera. If an error has been produced in appointing the photographing position, the foregoing frame can be fixed to a predetermined position, so that the photographing operation is continued.
According to another aspect of the present invention, there is provided an image processing apparatus comprising: gate means for fetching an image signal corresponding to the inside of a predetermined region in a frame; appointing means for inputting position setting information for appointing a set position of the predetermined region in the frame; position setting means that controls the gate means in accordance with an output from the appointing means to control the position of the predetermined region in the frame; and control means for maintaining the predetermined region at a state immediately before an error is made if the error is made in an operation of setting the position of the predetermined region by the appointing means.
As a result, even if the appointing means has produced an error, the operation state is not immediately changed. However, if the error ends in a short time, the state of the gate means is maintained on the basis that information about the latest set position obtained is correct such that the system is stabilized.
According to another aspect of the present invention, there is provided an image processing apparatus comprising: gate means for processing an image signal corresponding to the inside of a predetermined region in a frame; appointing means for inputting set position information for appointing a set position of the predetermined region in the frame; position setting means that controls the gate means in accordance with an output from the appointing means to control the position of the predetermined region in the frame; and control means for forcibly moving the predetermined region to a predetermined position in the frame regardless of setting performed by the appointing means if an error is made over a predetermined period in an operation for setting the position of the predetermined region by the appointing means.
As a result, if an error in the operation for setting the region, in which image is fetched, has been produced for a long time, the predetermined region is forcibly fixed to a predetermined position so that the image processing operation is stabilized.
A third object of the present invention is to provide an image pickup apparatus and an image processing apparatus, such as a video camera using a region setting means using detection of the line of sight or the like, which is capable of overcoming the problem that the set position has undesirably moved and an error is therefore produced due to blinking, looking the other way or the like.
If the result of the detection has a probability of an error being made due to scattering of the line of sight, blinking of the photographer, or noise and the like and therefore the result is not reliable, updating the present central coordinates is inhibited. Therefore, undesirable movement of the fetched region, such as the focal point detection region or the photometry region due to scattering of the line of sight, blinking of the photographer, or noise and the like can be prevented. Thus, focal-point control, exposure control and display of the region in the frame can be stabilized.
A fourth object of the present invention is to provide an image-signal processing apparatus in which the region display for an operator is optimized in a mode in which a region to be processed in the screen, such as the range-finding frame or the photometry frame, is made variable in a mode in which the range finding and the photometry are performed in a fixed region.
A fifth object of the present invention is to provide a video camera apparatus in which the AF characteristic is made different between a mode in which detection of the line of sight is performed to vary the position of the range-finding frame at the time of performing the AF operation and a mode in which the AF operation is performed in a fixed range-finding frame so as to be optimized for the selected mode.
A sixth object of the present invention is to provide a video camera apparatus using a position setting means, which employs detection of the line of sight or uses a joy stick or a track ball to move the photometry frame to optimize the exposure control.
Other and further objects, features, and advantages of the invention will be evident from the following detailed description of the preferred embodiments in conjunction with the attached drawings.